How to Install JDK in Linux

Using Debian

1. 
   Press Ctrl+Alt+T to open a new terminal window. If you're already at the command prompt, just skip to the next step.
2. 
   Type su - and press ↵ Enter.
3. 
   Add the Linux Uprising repository. Here's how:

   1. Type echo "deb http://ppa.launchpad.net/linuxuprising/java/ubuntu bionic main" and press ↵ Enter.
   2. Type apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 73C3DB2A and press ↵ Enter.
4. 
   Type apt-get update and press ↵ Enter.
5. 
   Type apt-get install oracle-java12-installer and press ↵ Enter.
6. 
   Type exit and press ↵ Enter. JDK is now installed.
7. 
   Type sudo apt install oracle-java12-set-default and press ↵ Enter. This sets Java 12 as the default Java version.

   1. To double-check the default version, type java --version at the command prompt and press ↵ Enter.